/*
 * Copyright 2016 The Cartographer Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef CARTOGRAPHER_MAPPING_2D_PROBABILITY_GRID_H_
#define CARTOGRAPHER_MAPPING_2D_PROBABILITY_GRID_H_

#include <vector>

#include "cartographer/common/port.h"
#include "cartographer/mapping/2d/grid_2d.h"
#include "cartographer/mapping/2d/map_limits.h"
#include "cartographer/mapping/2d/xy_index.h"

namespace cartographer {
	namespace mapping {

		// Represents a 2D grid of probabilities.
		/*
		* ProbabilityGrid是从Grid2D派生而来的，在它的定义中没有额外的添加成员变量，它只是通过一些函数来解释栅格单元的占用概率。
		*/
		class ProbabilityGrid : public Grid2D {
		public:
			//limits用于描述地图的边界
			explicit ProbabilityGrid(const MapLimits& limits, ValueConversionTables* conversion_tables);

			explicit ProbabilityGrid(const proto::Grid2D& proto, ValueConversionTables* conversion_tables);

			// Sets the probability of the cell at 'cell_index' to the given
			// 'probability'. Only allowed if the cell was unknown before.
			//赋予单元索引cell_index概率值probability
			void SetProbability(const Eigen::Array2i& cell_index, const float probability);

			// Applies the 'odds' specified when calling ComputeLookupTableToApplyOdds()
			// to the probability of the cell at 'cell_index' if the cell has not already
			// been updated. Multiple updates of the same cell will be ignored until
			// FinishUpdate() is called. Returns true if the cell was updated.
			//
			// If this is the first call to ApplyOdds() for the specified cell, its value
			// will be set to probability corresponding to 'odds'.
			bool ApplyLookupTable(const Eigen::Array2i& cell_index, const std::vector<uint16>& table);

			GridType GetGridType() const override;

			// Returns the probability of the cell with 'cell_index'.
			float GetProbability(const Eigen::Array2i& cell_index) const;

			proto::Grid2D ToProto() const override;

			std::unique_ptr<Grid2D> ComputeCroppedGrid() const override;

			bool DrawToSubmapTexture(
				proto::SubmapQuery::Response::SubmapTexture* const texture,
				transform::Rigid3d local_pose) const override;

		private:
			ValueConversionTables* conversion_tables_;
		};

	}  // namespace mapping
}  // namespace cartographer

#endif  // CARTOGRAPHER_MAPPING_2D_PROBABILITY_GRID_H_
